The objective is to identify the regimens of intravenously (IV) administered pantoprazole that would decrease and maintain acid secretion at less than 10mEq/hr in patients with Zollinger-Ellison syndrome (ZES) with or without multiple endocrine neoplasia-type I (MEN- I) syndrome who have not undergone partial gastrectomy and at less than 5 mEq/hr in those patients with ZES with or without MEN-I who have undergone partial gastrectomy and to minor safety.